WASHINGTON — Prominent vaccine skeptic Robert F. Kennedy Jr. said Wednesday that he expects the Trump administration to move forward with a vaccine safety commission and that President Trump pledged that he was “not going to back down” if the drug industry objected to the commission.

Kennedy said he had spoken with presidential aides three times since his January meeting with Trump. His understanding is that a commission is still being developed, he said.

“Why would anybody not want a vaccine safety commission?” he said at an event with actor Robert De Niro at the National Press Club in Washington.

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Kennedy said Trump’s transition team first called him in December and he first spoke with the president-elect by phone in early January. According to Kennedy, Trump said he knew the pharmaceutical industry would combat any efforts to question vaccine safety. “I’m not going to back down,” Trump said, according to Kennedy.

Trump, Kennedy recalled, said he had five friends whose children seemed to have changed after receiving vaccines.

Kennedy’s meeting at Trump Tower sparked outrage from scientists and public health experts, who fear the administration could give legitimacy to skeptics of childhood immunizations despite scientific research demonstrating that vaccines are safe. Many of those skeptics believe vaccines are a cause of autism.

After the meeting, Kennedy said, Trump’s staff told him to speak with reporters about his discussions with the president. Hours later, however, a spokeswoman for Trump said “no decisions have been made at this time” about a possible vaccine panel.

On Wednesday, Kennedy told reporters that Trump aides called him after the meeting and said they had “got out over our skis” and the concept still needed to be vetted.

He added that, although he expected the commission to be established, “I can’t tell you what’s going to happen.”

He said that if the commission moved forward, he would want members without existing prejudices on the issue. He said he also expected the panel would make “mild recommendations,” particularly regarding alleged conflicts of interest at the Centers for Disease Control and Prevention.